Work

Relating flow resistance to equivalent roughness

Year: 2024

Type: article

Abstract: Describing flow resistance using the physical properties of an underlying surface is a recalcitrant problem in overland flow models. If discharge measurements are available, an equivalent roughness (e.g., Manning's n) can be calibrated to represent the effects of surface properties within the domain with a single numerical value. Alternatively, the flow resistance can be estimated from discharge and velocity measured at a point, typically a runoff plot outlet. However, such experimental estimates are often inconsistent with the equivalent roughness determined from calibration to discharge, even if both derive from the same dataset. For example, if Manning's equation is used to parameterise flow resistance, the Manning's n obtained by calibrating a model to discharge differs from the value of n calculated from measured flow and velocity at the hillslope outlet. Here, this discrepancy is resolved by deriving a correction factor relating experimentally-determined flow resistance to the calibrated roughness. The derived correction factor is tested for four commonly-used resistance formulations using 129 rainfall simulator experiments. The correction factor is necessary to reproduce measured velocities, and yields minor improvements in discharge prediction.

Source: Advances in Water Resources

DOI: 10.1016/j.advwatres.2024.104855

Authors: Octavia Crompton, Gabriel Katul, Sally E. Thompson

Institutions: Agricultural Research Service, United States Department of Agriculture, Duke University, The University of Western Australia

Language: English

Topic: Hydrology and Watershed Management Studies

Subfield: Water Science and Technology

Field: Environmental Science

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,730

Funders: National Science Foundation, U.S. Department of Energy